The nose is responsible for warming, humidifying and filtering inspired air and for conserving heat and moisture from expired air. The nose is formed mainly of cartilage, bone, mucous membranes and skin.
The bones in the nose contain a series of cavities known as paranasal sinuses that are connected by passageways. The paranasal sinuses include frontal sinuses, ethmoid sinuses, sphenoid sinuses and maxillary sinuses. The paranasal sinuses are lined with mucous-producing epithelial tissue and ultimately opening into the nasal cavity. Normally, mucous produced by the epithelial tissue slowly drains out of each sinus through an opening known as an ostium. If the epithelial tissue of one of these passageways becomes inflamed for any reason, the cavities which drain through that passageway can become blocked. This blockage can be periodic (resulting in episodes of pain) or chronic. This interference with drainage of mucous (e.g., occlusion of a sinus ostium) can result in mucosal congestion within the paranasal sinuses. Chronic mucosal congestion of the sinuses can cause damage to the epithelium that lines the sinus with subsequent decreased oxygen tension and microbial growth (e.g., a sinus infection).
Sinusitis:
The term “sinusitis” refers generally to any inflammation or infection of the paranasal sinuses caused by bacteria, viruses, fungi (molds), allergies or combinations thereof. It has been estimated that chronic sinusitis (e.g., lasting more than 3 months or so) results in 18 million to 22 million physician office visits per year in the United States.
Patients who suffer from sinusitis typically experience at least some of the following symptoms:                headaches or facial pain        nasal congestion or post-nasal drainage        difficulty breathing through one or both nostrils        bad breath        pain in the upper teethThus, one of the ways to treat sinusitis is by restoring the lost mucous flow. The initial therapy is drug therapy using anti-inflammatory agents to reduce the inflammation and antibiotics to treat the infection. A large number of patients do not respond to drug therapy. Currently, the gold standard for patients with chronic sinusitis that do not respond to drug therapy is a corrective surgery called Functional Endoscopic Sinus Surgery.Current and Proposed Procedures for Sinus Treatment:        
Functional Endoscooic Sinus Surgery
In FESS, an endoscope is inserted into the nose and, under visualization through the endoscope, the surgeon may remove diseased or hypertrophic tissue or bone and may enlarge the ostia of the sinuses to restore normal drainage of the sinuses. FESS procedures are typically performed with the patient under general anesthesia.
Although FESS continues to be the gold standard therapy for surgical treatment of severe sinus disease, FESS does have several shortcomings. For example, FESS can cause significant post-operative pain. Also, some FESS procedures are associated with significant postoperative bleeding and, as a result, nasal packing is frequently placed in the patient's nose for some period of time following the surgery. Such nasal packing can be uncomfortable and can interfere with normal breathing, eating, drinking etc. Also, some patients remain symptomatic even after multiple FESS surgeries. Additionally, some FESS procedures are associated with risks of iatrogenic orbital, intracranial and sinonasal injury. Many otolaryngologists consider FESS an option only for patients who suffer from severe sinus disease (e.g., those showing significant abnormalities under CT scan). Thus, patients with less severe disease may not be considered candidates for FESS and may be left with no option but drug therapy. One of the reasons why FESS procedures can be bloody and painful relates to the fact that instruments having straight, rigid shafts are used. In order to target deep areas of the anatomy with such straight rigid instrumentation, the physician needs to resect and remove or otherwise manipulate any anatomical structures that may lie in the direct path of the instruments, regardless of whether those anatomical structures are part of the pathology.
Balloon Dilation Based Sinus Treatment
Methods and devices for sinus intervention using dilating balloons have been disclosed in U.S. Pat. No. 2,525,183 (Robison) and United States Patent Publication No. 2004/0064150 A1 (Becker). For example, U.S. Pat. No. 2,525,183 (Robison) discloses an inflatable pressure device which can be inserted following sinus surgery and inflated within the sinus. The patent does not disclose device designs and methods for flexibly navigating through the complex nasal anatomy to access the natural ostia of the sinuses. The discussion of balloon materials is also fairly limited to thin flexible materials like rubber which are most likely to be inadequate for dilating the bony ostia of the sinus.
United States patent publication number 2004/0064150 A1 (Becker) discloses balloon catheters formed of a stiff hypotube to be pushed into a sinus. The balloon catheters have a stiff hypotube with a fixed pre-set angle that enables them to be pushed into the sinus. In at least some procedures wherein it is desired to position the balloon catheter in the ostium of a paranasal sinus, it is necessary to advance the balloon catheter through complicated or tortuous anatomy in order to properly position the balloon catheter within the desired sinus ostium. Also, there is a degree of individual variation in the intranasal and paranasal anatomy of human beings, thus making it difficult to design a stiff-shaft balloon catheter that is optimally shaped for use in all individuals. Indeed, rigid catheters formed of hypotubes that have pre-set angles cannot be easily adjusted by the physician to different shapes to account for individual variations in the anatomy. In view of this, the Becker patent application describes the necessity of having available a set of balloon catheters, each having a particular fixed angle so that the physician can select the appropriate catheter for the patient's anatomy. The requirement to test multiple disposable catheters for fit is likely to be very expensive and impractical. Moreover, if such catheter are disposable items (e.g., not sterilizable and reusable) the need to test and discard a number of catheters before finding one that has the ideal bend angle could be rather expensive.
Thus, although the prior art discloses the use of dilating balloons for sinus treatments, it does not disclose the various means for navigation through the complex anatomy without significant manipulation of non-pathogenic anatomical regions that obstruct direct access to the sinus openings. Further, the prior art only discloses balloons of relatively simple shapes or materials for dilating sinus openings. Further, this art does not sufficiently elaborate beyond endoscopy on other means for imaging or tracking the position of such devices within the sinus anatomy.
Thus, there is a need for new devices and methods for easily navigating the complex anatomy of the nasal cavities and paranasal sinuses and for treating disorders of the paranasal sinuses with minimal complications due to individual variations in anatomy and causing minimal trauma to or disruption of anatomical structures that are not pathogenic.